1. Field of the Invention
This invention relates to a frequency conversion laser head with improved heat-diffusing capabilities.
2. Prior Art
Frequency converting laser heads are used in numerous fields including, but not limited to industrial and medical applications. Not all wavelength regions of interest are directly accessible with laser. Therefore, it is common to generate visible light by nonlinear conversion of light. Typically a beam of light of a narrow wavelength illuminates a nonlinear component which doubles, triples and etc. the output frequency of the light.
In a nonlinear frequency conversion process the efficiency of conversion of laser power at a fundamental frequency into power at combined frequencies, such as the second, third and other harmonic frequencies, is strongly dependent on the intensity of radiation interacting with the non-linear optical material. In practice, high intensities are needed to reach laser output powers up to tens of watts and higher so desirable by the market. The high intensities are accompanied by elevated temperatures which are detrimental to the desired functionality of a laser head explained in detail immediately hereinbelow.
Referring to FIG. 1, a laser unit 10 includes a laser module 12 and a frequency conversion laser head 14. The laser module 12 may be configured as a solid state or all fiber laser outputting a pump light at a fundamental frequency. The pump light is coupled to an output component 16 and delivered to laser head 14 where it impinges upon a frequency conversion component. The latter, in turn, converts the fundamental frequency of the pump radiation into the desired frequency. The output light at the desired frequency is finally delivered to the object to be treated.
Not all of the pumped radiation is converted into the desired frequency. In fact, only a small portion of the pumped light is usefully converted; the other, large portion of the pumped radiation remains unchanged and, therefore, useless. For example, the pump light, coupled to laser head 14, has a power of 10 W. As a result of the frequency conversion, the output light delivered to the object to be treated at the desired frequency has a power of about 2 W. The other 8 watts of the pump light exiting the non-linear frequency component at the fundamental frequency create a thermally-hazardous situation within laser head 14, which can possibly lead to a completely unsatisfactory operation of the laser. To somewhat minimize the thermal effect, the laser head has a greater volume that renders it space-ineffective. Yet, to the best of the applicant's knowledge, this configuration of the laser head is predominant in the laser industry.
It is, therefore, desirable to provide a frequency conversion laser head configured to minimize the thermal effect of the unconverted pump radiation.
It is also desirable to provide a laser assembly configured with the improved frequency conversion laser head, as disclosed immediately above.